Carbohydrates are eaten either as simple sugars or as more complex molecules called polysaccharides, which are built up from simple sugar units and of which the starch of potatoes, bread, etc., is a well-known example. The body absorbs carbohydrates from the small intestine in the form of single sugar units, or monosaccharides. Those sugars which are ingested in this form, e.g., glucose in various "energy-giving" preparations and fructose, the sugar of fruit, thus require no further treatment. Sugar molecules bigger than this require enzymic digestion.
The digestion of starch begins in the mouth. Saliva contains an enzyme, amylase, which attacks starch and similar polysaccharides, reducing the size of the molecule. Starch is made up of chains of glucose molecules linked in a particular way, and amylase attacks the links between the glucose units. The enzyme acts at many points in the chain, and the smallest units it produces are molecules of the sugar maltose. Maltose is made up of two glucose units; this sugar is thus a disaccharide. ##SPC1##
Starch also contains branched chains of glucose units, and the amylase of saliva cannot break the chains at the points where branching occurs: ##SPC2##
If the branched-chain structure of starch is thought of as resembling a bush, the enzyme can prune the outer branches until it reaches a fork and then its action stops. Thus, as well as molecules of maltose, amylase produces from starch fragments of the original molecule which are like hard-pruned bushes and which are called "limit dextrins". Glycogen, the carbohydrate storage material of animal tissues, is also made up of much-branched chains of glucose units.
The digestion of starch or glycogen by salivary amylase probably does not get very far, however. The process continues for a while after the food has entered the stomach, but as the acid of the gastric juice penetrates through the food mass the amylase action slows down and stops. The main attack on these polysaccharides takes place in the small intestine by an amylase in pancreatic juice similar to that in saliva.
The dextrins resulting from the "pruning" by amylase are attacked by an enzyme in the small intestine which can break the inter-chain links. A specific enzyme, maltase, also splits each molecule of maltose produced from starch into two molecules of glucose, which are then absorbed and metabolized by the body. Some of the sugars of food are disaccharides; common sugar (sucrose) is made up of a molecule of glucose joined to a molecule of fructose, and lactose (the sugar of milk) is also a disaccharide. These sugars are split into their component monosaccharides by specific enzymes in the intestine.
However, in the treatment of conditions in which there is an indication of obesity, adipose, hyperlipidemia (arteriosclerosis), diabetes, pre-diabetes, gastritis, gastric ulcer, duodenal ulcer, and/or caries, it is necessary that such glycosidehydrolase enzyme be inhibited or suppressed in such a manner that they cannot further catalyze the breakdown thereof, as indicated in the manner above for subsequent utilization by the body and thus further promotion or worsening of the condition being treated.
It has been known heretofore that .alpha.-amylases can be inhibited by the use of various low molecular substances, such as, for example, salicylic acid and abiscisin [T. Hemberg, J. Larsson, Physiol. Plant. 14, 861 (1961), T. Hemberg, Acta Chem. Scand. 21, 1665 (1967)]. It is further known that there are also higher-molecular substances which are capable of inhibiting the activity of certain amylases non-specifically by physical adsorption [T. Chrzaszcz, J. Janicki, Bioch. Z. 260, 354 (1933) and Bioch. J. 28, 296 (1934)] or by denaturation and precipitation of the enzyme [B. S. Miller, E. Kneen, Arch. Biochem. 15, 251 (1947), D, H. Struhmeyer, M. H. Malin, Biochem. Biophys. Acta 184, 643 (1969)]. It has also been observed that it is possible to elute a substance from wheat by means of distilled water, which lowers the dextrifying activity of salivary amylase but has little influence on the activity of pancreatic amylase [E. Kneen, R. M. Sandstedt, Arch., Bioch. 9, 235 (1946)].
It is a disadvantage of these known inhibitors that either the inhibition of the amylase is non-specific or that the inhibiting activity of the inhibitor is slight, especially on pancreatic amylases, as has been shown by our own investigations; that is to say, only at very high ratios of inhibitor: enzyme is almost complete inhibition of the amylases (up to 90% and above) attained.
An earlier proposal (United States patent application Ser. No. 110,482, filed Jan. 28, 1971, now abandoned) relates to amylase inhibitors. In fact, the older proposal shows that by means of aqueous electrolyte solutions, preferably dilute acids, or above all by means of water-alcohol (C.sub.1 -C.sub.3 -alcohols) mixtures, preferably at acid pH values, a highly active inhibitor for pancreatic amylase, which does not show the disadvantages mentioned, can be extracted in high yields from wheat (coarse ground wheat, wheat flour or wheat gluten). The substance thus obtained inhibits pancreatic amylase to the extent of more than 90% even at very low inhibitor:enzyme ratios.